Energy & Enzymes
Metabolism is the sum of chemical processes that occur in living organisms. These metabolic pathways are catalyzed by:
a. Substrates
b. Enzymes
c. Amino acids
d. Inhibitors
b. Enzymes
The chemical substance that supplies most of the immediate energy that drives metabolism and serves as the currency of energy in a cell is _____.
a. AMP
b. ADP
c. ATP
d. none of the above
c. ATP
Which of the following is not a type of cellular work that requires ATP?
a. Passive Transport
b. Active Transport
c. Anabolism
d. Mechanical Work
a. Passive Transport
During cell communication in the nervous system, chemical messengers called neurotransmitters travel between neurons. As they travel, neurotransmitters send messages from one neuron to another. Which of the following best describes the role of neurotransmitters in cell-to-cell communication?
a. Neurotransmitters are local regulators that allow neurons to communicate over short distances.
b. Neurotransmitters are local regulators that allow neurons to communicate over long distances.
c. Neurotransmitters are long-distance signaling molecules that allow neurons to communicate over short distances.
d. Neurotransmitters are long-distance signaling molecules that allow neurons to communicate over long distances.
a. Neurotransmitters are local regulators that allow neurons to communicate over short distances.
Which of the following statements best explains the mechanism for DNA replication?
a. DNA replication is reductive, because half the total DNA present is copied.
b. DNA replication is semi-conservative, because each DNA strand serves as a template during replication.
c. DNA replication is dispersive, because the two resulting DNA molecules are mixtures of parent and daughter DNA.
d. DNA replication is conservative, because one resulting molecule is identical to the original and the other consists of two new strands.
b. DNA replication is semi-conservative, because each DNA strand serves as a template during replication.
_____ is the metabolic process of synthesizing new molecules from smaller components. _____ is the metabolic process breaking down large molecules to smaller components.
a. anabolism; catabolism
b. anabolism; anabolism
c. catabolism; catabolism
d. catabolism; anabolism
a. anabolism; catabolism
Energy coupling uses the energy released from _____ reactions, such as ATP hydrolysis, to drive _____ reactions, such as ATP synthesis.
a. exergonic; exergonic
b. exergonic; endergonic
c. endergonic; exergonic
d. endergonic; endergonic
b. exergonic; endergonic
Which of the following is the only step in aerobic cellular respiration that does not produce ATP?
a. Glycolysis
b. Pyruvate oxidation
c. Kreb's Cycle
d. Oxidative phosphorylation
b. Pyruvate oxidation
Epinephrine will bind to GPCR which in turn activates the G protein. The G protein will activate the adenylyl cyclase which converts ATP to cAMP. cAMP will initiate the signal transduction phase by activating the first kinase in the phosphorylation/dephosphorylation series. In this example, epinephrine is the _____ messenger and cAMP is the _____ messenger.
a. first; first
b. first; second
c. second; first
d. second; second
b. first; second
In DNA replication, DNA "unwinds" to form two template strands: the leading strand and the lagging strand. Which of the following statements about these strands is true?
a. Okazaki fragments are used to synthesize the leading strand of DNA.
b. The leading strand of DNA is synthesized continuously.
c. DNA polymerase can only synthesize DNA on the leading strand.
d. The lagging strand can only be synthesized once the leading strand has been completed.
b. The leading strand of DNA is synthesized continuously.
An endergonic reaction . . .
a. is spontaneous
b. releases energy
c. a reaction where reactants have more free energy than products
d. a reaction where products have more free energy than reactants.
d. a reaction where products have more free energy than reactants.
The chemical equation for cellular respiration is as follows: C6H1206 + 6O2 -> 6CO2 + 6 H2O + ENERGY.
Which molecule is oxidized? Which molecule is reduced?
a. oxygen; water
b. glucose; water
c. oxygen; glucose
d. glucose; oxygen
d. glucose; oxygen
Unlike most other cells in the human body, mature red blood cells (RBCs) do not contain a nucleus or mitochondria. This allows RBCs to carry more hemoglobin, and therefore oxygen, through the bloodstream. Which of the following is true about RBCs?
a. RBCs generate lactate as a waste product.
b. Oxygen is used as the terminal electron acceptor in RBCs.
c. CO2 and ethanol are byproducts of ATP production in RBCs.
d. Due to a lack of mitochondria, RBCs do not produce ATP.
a. RBCs generate lactate as a waste product.
(Because RBCs do not contain mitochondria, they generate ATP through fermentation. The type of fermentation that occurs in animal cells is lactic acid fermentation, which produces lactate as a byproduct. )
What is an example of long distance endocrine signaling?
a. Neurotransmitters being secreted across a synapse to stimulate a muscle cell.
b. Cells transporting nutrients through gap junctions.
c. Pancreas releasing insulin into the blood.
c. A cell secreting interleukins to itself.
c. Pancreas releasing insulin into the blood.
There are several DNA repair mechanisms in place to help detect and correct DNA damage. Which of the following is true regarding these DNA repair mechanisms?
a. DNA damage from chemical reactions cannot be undone.
b. Proofreading from DNA polymerase reduces the error rate in DNA to about 1 in 10 nucleotides.
c. Copying errors not caught by the replication machinery can be corrected by mismatch repair.
d. Non-homologous end joining is less likely to produce mutations than homologous recombination.
c. Copying errors not caught by the replication machinery can be corrected by mismatch repair.
A molecule binds to an enzyme inducing a conformational change that changes the shape of the active site of the enzyme. This is an example of:
a. competitive inhibition
b. noncompetitive inhibition
c. allosteric regulation
d. two of the choices above are correct
d. two of the choices above are correct
NAD+/NADH are energy storing/carrying molecules that transport electrons to the ETC. Which molecule is the oxidized form, and which is the reduced form?
a. NAD+/NADH
b. NAD+/NAD+
c. NADH/NAD+
d. NADH/ NADH
a. NAD+/NADH
Bacteroides is the predominant genus of bacteria found in the human gut microbiota. As anaerobic bacteria, Bacteroides undergo fermentation in the gut, converting otherwise nondigestible carbohydrates into fermentation products that are used by the host for energy. Which of the following toxins would be most likely to disrupt carbohydrate metabolism in Bacteroides species?
a. A toxin that inhibits the function of ATP synthase.
b. A toxin that breaks down the membrane proteins of the electron transport chain.
c. A toxin that inhibits the function of an enzyme during glycolysis.
d. A toxin that prevents the formation of Krebs cycle products.
c. A toxin that inhibits the function of an enzyme during glycolysis.
(According to the text, Bacteroides break down carbohydrates through fermentation. The first step of fermentation is glycolysis, so a toxin that inhibits the function of a glycolytic enzyme would also disrupt carbohydrate metabolism in Bacteroides species. )
Ligands are signaling molecules that can elicit a cellular response. The ligands that membrane receptors bind to outside of the cell are _____, while the ligands that intracellular receptors bind to in the cytosol are small & _____.
a. hydrophobic; hydrophilic
b. hydrophobic; hydrophobic
c. hydrophilic; hydrophilic
d. hydrophilic; hydrophobic
a. hydrophobic; hydrophilic
Nucleosomes are the basic unit of packaged DNA. Nucleosomes can exist in thin, unwound fibers known as _____ or can condense into thick, coiled-like structures known as _____.
a. chromosome; chromatin
b. chromosome; chromosome
c. chromatin; chromatin
d. chromatin; chromosome
d. chromatin; chromosome
What kind of bonds hold the enzyme and substrate together?
a. ionic bonds
b. covalent bonds
c. noncovalent bonds
d. all of the above
c. noncovalent bonds
ATP synthase is an enzyme that produces ATP using the energy from the proton gradient created by the electron transport chain. This two-part process is known as _____.
a. substrate-level phosphorylation
b. oxidative phosphorylation
c. ETC
d. chemiosmosis.
b. oxidative phosphorylation
Cyanide poisoning is a type of poisoning caused by exposure to certain cyanide-containing compounds, such as hydrogen cyanide or cyanide salts. Inhalation or consumption of these compounds can cause histotoxic hypoxia, a condition in which cells are no longer able to take up or utilize oxygen during cellular respiration. As a result, ATP production during respiration is significantly reduced. which of the following is the most likely explanation for how cyanide causes histotoxic hypoxia?
a. Cyanide inhibits the transport of pyruvate across the mitochondrial membrane.
b. Cyanide inhibits the transfer of electrons to the final acceptor in the electron transport chain.
c. Cyanide inhibits the enzymatic breakdown of glucose during glycolysis.
d. Cyanide inhibits the reduction of NAD+ and FAD during the Krebs cycle.
b. Cyanide inhibits the transfer of electrons to the final acceptor in the electron transport chain.
(The final electron acceptor in the electron transport chain is oxygen. By inhibiting the transfer of electrons to oxygen, cyanide shuts down the electron transport chain, halting ATP synthesis and causing histotoxic hypoxia. )
A mutation causes the extracellular domain of a G protein-coupled receptor (GPCR) to be misfolded. The misfolded GPCR is packaged into a vesicle that travels to the cell membrane. Upon reaching the cell membrane, the vesicle deposits the misfolded GPCR, which fuses with the cell membrane and functions as a membrane receptor.
a. The intracellular domain of the misfolded GPCR will change from an inactive to an active shape.
b. The extracellular domain of the misfolded GPCR will begin a signal transduction pathway.
c. The ligand-binding domain of the misfolded GPCR will not bind with it's specific ligand.
d. The intracellular domain of the misfolded GPCR will not bind with it's specific ligand.
c. The ligand-binding domain of the misfolded GPCR will not bind with it's specific ligand.
(The ligand-binding domain of a GPCR must have the correct shape to bind with its ligand. If the GPCR is misfolded, the ligand-binding domain will change shape. As a result, the domain will no longer be able to bind with its specific ligand. )
1. _____ opens up the DNA at the replication fork.
2. _____ works at the region ahead of the replication fork to prevent supercoiling.
3. _____ synthesizes RNA primers complementary to the DNA strand.
4. _____ seals the gaps between DNA fragments.
a. Ligase
b. Helicase
c. Topoisomerase
d. Primase
1. b. Helicase
2. c. Topoisomerase
3. d. Primase
4. a. Ligase